DFT Characterization of Solvated NaCl Potentials of Mean Force and Energetics

Potentials of mean force have long been a standard of measurement to characterize the energetics of the ion solvation process. In particular, classical molecular dynamics simulations frequently predict deeper minima than DFT simulations for the different solvated states. Moreover, different exchange-correlation functionals often don't yield consistent potentials within DFT, some even predicting more stable second minima (solvent-separated ion pairs) than the usual deepest first minimum (contact ion pair). In this work, we investigate the electronic structure of solvated NaCl and the effects the charge localization has on nearby water molecules. We further investigate the errors in the system arising from the functional approximations and from the self-consistent ground-state Kohn-Sham electron density, and how the errors contribute to different stability characteristics.